1. Field of the invention
The present invention relates to a stereoscopic microscope in which real images of an object are respectively formed by a pair of objective optical systems, which are separately placed with a predetermined base length therebetween, and in which the real images are relayed by another optical system.
2. Description of the Related Art
This type of video-type stereoscopic microscope is used when tiny tissues, such as a brain, are operated.
Since it is difficult to observe a structure of an organ consisting of tiny tissues, such as a brain, by direct viewing, the operations for such an organ must be proceeded under a microscope. Besides, since it is impossible to observe the three-dimensional structure of a tissue with a monocular microscope, a stereoscopic microscope has been used to enable three-dimensional magnifying observation of the tissue in order to perform accurate operations.
Such stereoscopic microscope is classified into an optical type one and a video type one. In either type of the stereoscopic microscope, an optical structure, in which a pair of objective optical systems separately placed with a predetermined base length therebetween to respectively form real images of same object, is adopted. In the optical-type stereoscopic microscope, a pair of real images (that is, a pair of primary images) once formed by the pair of objective optical systems are transferred through a pair of eyepieces as virtual images, and the virtual images are observed by an observer. On the other hand, in the video-type stereoscopic microscope, a pair of real images are relayed through a pair of relay optical systems to re-form the respective images on an image taking surface of an image pickup device.
In the stereoscopic microscopes with those constructions, the positions of the primary images of same object formed by the pair of objective optical systems may deviate from each other in the direction of the optical axes of the optical systems, because of manufacturing errors possible to occur in each objective optical system, or of installation errors possible to occur on the objective optical systems with respect to the housing. In such cases, adjusting the eyepiece optical system or relay optical systems for transmitting the primary images may be conducted to adjust the focal condition of the final images to be picked up or observed.
However, when the optical systems that are disposed after the primary images are adjusted, there could be a drawback that the magnification and the size of the final images may be different between the left and right optical systems. In order to eliminate the occurrence of the drawbacks, such as the difference of magnification and position of image, an operator has to conduct the adjustment of the entire optical system after adjusting eyepiece optical systems and/or the relay optical systems so that the focal conditions and the magnifications of the resultant images may be matched between the right and the left optical systems. That also causes a problem that the entire adjustment procedures become too complicated.